1. Field of the Invention
The present invention relates to a bar magazine for lathes equipped with a bar-centering instrument designed principally to attenuate the vibrations of the bar in the loading channel and in particular during high speed machining of small-diameter bars.
2. State of the Prior Art
The problem of avoiding vibrations of bars in the channels of magazines and holding them in the correct position during machining in lathes (for example a plurimandrel lathe) is known in the prior art. In particular, there are serious problems when the bars have a diameter much smaller than that of the magazine channel and when the machining is done at high rotation speeds as often happens in the more modern machines. Under these conditions, indeed, the vibrations are quite accented and, in addition to causing considerable noise, they lead to the production of machined pieces out of tolerance.
To remedy these problems it is proposed to insert adaptors to be fitted in the channel so as to leave little freedom of movement to the bar and thus reduce its vibrations. However, this solution brings on the need to replace the entire bar-pusher each time it is desired to machine a small-diameter bar. This fact, in addition to the need of having available several bar-pushers with different dimensions, also involves the need to stop the machine for long periods to insert the adaptors in the channel and change the bar-pusher. It is also noted that when the bar is shaped (for example with a hexagonal or square cross section) the diameter reduction proposed in the prior art causes considerable vibration problems contrary to what is desired.
The general purpose of the present invention is to remedy the above mentioned shortcomings by making available a lathe bar-magazine which would avoid strong vibration of the bars, even when their diameter is much less than the diameter of the channel and the rotation speed of the bar is high, while avoiding having to stop the machine for long periods when changing the diameter of the bar being machined.
Another purpose of the present invention is to make available a bar magazine for lathes that while ensuring satisfactory centering of small-diameter bars in the loading channel would keep a simple and economical structure compared with prior art magazines.